1. Field of the Invention
The present invention relates to an image forming apparatus having an exposure device in which an exposure lamp is stored, and more particularly to an image forming apparatus for exchanging a stored exposure lamp safely and easily.
2. Description of Related Art
Generally, in an image forming apparatus having an exposure device, a halogen lamp or other types of lamps are used as a light source for exposing an original. In an image forming apparatus which uses a photosensitive and pressure-sensitive recording sheet, the recording sheet is exposed by a large amount of light. The halogen lamp irradiates at a high luminance energy by receiving a high current, and consequently the lamp quickly degrades and must therefore be frequently replaced.
Recently, it has become desirable to operate an image forming apparatus at high speeds. At high speeds it is necessary to shorten the exposing time and thus the amount of luminous energy supplied to the light source of the exposure device must be increased. Therefore, it has become a practice to use a light source having a large luminous energy by greatly increasing the wattage of the light source. Consequently, durability of the light source is shortened and it is necessary to exchange the light source often.
Image forming apparatuses using an exposing method use either a slit exposing method or a whole surface exposing method. The slit exposing method can use either a movable light source or a fixed light source. A halogen lamp, a fluorescent lamp, a flash lamp and other lamps are used as the light source.
In any of the above described exposing methods, a cover member placed at the upper portion of the lamp house should be opened at first so as to exchange the halogen lamp, since the halogen lamp is stored in the lamp house. When the exposure lamp is exchanged, it is an obligation to turn off a switch for safety. However, it is possible to exchange the lamp without turning off the switch due to laziness or forgetfulness. If the lamp is exchanged without turning off the switch, there is a risk that an operator will be struck by high amounts of electricity. In an image forming apparatus using the slit exposing method in which a lamp is fixed, an original support stand is moved and a lamp house cover member is placed below the position where the original support stand is located before it begins moving. When changing the lamp, the operator opens the lamp house cover member. After the lamp is exchanged, if the operator pushes a copying switch button without closing the lamp house cover member, the lamp house cover member can be damaged by the original support stand moving horizontally.
Furthermore, in any of the above described exposing methods, a reflecting mirror is provided near the light source for directing light along a light path from the light source to the irradiated medium such as an original. Particularly, in a slit exposing method, a pair of oval-shaped reflecting mirrors are provided for partly surrounding the light source to condense the light from the light source into a slit shape. Conventionally, the reflecting mirrors are fixed near the light source and cannot be separated from the light source. Thus, in the above described conventional exposure device, the light source cannot be exchanged without removing the reflecting mirrors, since the reflecting mirrors are fixed near the light source. It is difficult to attach or detach the reflecting mirrors. Therefore, an exchanging operation requires much time and labor.